Hydrogen fuel cells and other hydrogen-consuming devices require a material medium that will readily absorb hydrogen for temporary storage and later release hydrogen upon demand of the hydrogen-fueled device. There is a need for a storage medium to which hydrogen gas may be added and withdrawn under moderate processing conditions. The need is particularly acute where the hydrogen-consuming device is used on a passenger or commercial vehicle to power it.
Various materials, such as metal hydride compositions, have been proposed to store and release hydrogen. Magnesium, for example, has a relatively high theoretical storage capacity (7.6% hydrogen at 300° C.) as MgH2, but the Mg/MgH2 combination may not presently be used for fuel cells because of its low sorption kinetics and its desorption temperature of about 350° C. These temperatures are perceived as being too high for vehicle applications. Hydrogen absorption and desorption temperatures of the order of 80° C. to 150° C. or lower are desired for many hydrogen storage applications.
Other magnesium-based hydride materials have been proposed, including magnesium-nickel alloys (with and without palladium catalyst particles), Mg—Nb2O5 composites, and others. But these other potential hydride materials present like impediments for hydrogen storage applications or provide low yields of hydrogen.
It is an object of this invention to provide a method of preparing hydride-materials for storage and release of hydrogen under more moderate conditions.